The present invention relates to a highly stable thin film resistor comprising an alloy of tantalum and chrome, which has a low resistance and a small temperature coefficient of resistance, and to a method of producing the same.
With the recent rapid development of the electronics industry, requirements for the electronic characteristics of circuit elements have become very severe. Conventionally, nichrome type materials have been mainly used as the resistance materials for making thin film circuits and individual resistors. For the purpose of improving the stability in performance of the thin film circuits and the resistors, tantalum nitride thin film resistors have been developed and are used in practice. The specific resistance of the tantalum nitride thin film resistors is about 260 .mu..OMEGA..cm and the sheet resistivities of the film resistors formed with a thickness for practical use are in the range of 50 to 200 .OMEGA./.quadrature.. However, the tantalum nitride thin film resistors are still poor in temperature characteristics and stability. Therefore, they cannot meet the present requirements for electric characteristics. Tantalum nitride forms an interstitial solid solution with nitrogen of small atomic radius, so that it has extremely high mechanical strength. However, tantalum nitride has a problem with respect to stability in electric characteristics at high temperatures. Furthermore, when the tantalum nitride thin film resistors are produced by a reactive sputtering method, it is required that slight amounts of active gases be introduced into a vacuum chamber, so that an extremely precise control technique is indispensable to that method.